This report concerns development projects which utilize synthetic membrane technology in support of biomedical research. One such project utilizes hydrophilic microporous membranes to achieve continuous ex vivo plasmapheresis for sampling blood plasma from an arteriovenous shunt of an animal. This sampling technique is useful in unsteady-state pharmacokinetic experiments requiring the time integral of the plasma free concentration of a chemical species whose distribution between plasma and the formed elements of the blood is in disequilibrium. A second project utilizes reverse osmosis or hydrophobic microporous membranes in hollow fiber configurations to concentrate an aqueous stream to be fed into a mass spectrometer. In the reverse osmosis concentrator water is driven from the feed stream by a transmembrane pressure difference, whereas the second type of concentrator uses heat to drive the water from the feed stream by evaporation through the membrane pores.